Wireless communication networks can generally be classified as either infrastructure-based wireless networks or ad hoc wireless networks.
An infrastructure-based wireless network typically includes a communication network with fixed and wired gateways. Many infrastructure-based wireless networks employ a mobile unit or host which communicates with a fixed base station that is coupled to a wired network. The mobile unit can move geographically while it is communicating over a wireless link to the base station. When the mobile unit moves out of range of one base station, it may connect or “handover” to a new base station and starts communicating with the wired network through the new base station.
In comparison to infrastructure-based wireless networks, such as cellular networks or satellite networks, ad hoc networks are self-forming networks which can operate in the absence of any fixed infrastructure, and in some cases the ad hoc network is formed entirely of mobile nodes. An ad hoc network typically includes a number of geographically-distributed, potentially mobile units, sometimes referred to as “nodes,” which are wirelessly connected to each other by one or more links (e.g., radio frequency communication channels). The nodes can communicate with each other over a wireless media without the support of an infrastructure-based or wired network. Links or connections between these nodes can change dynamically in an arbitrary manner as existing nodes move within the ad hoc network, as new nodes join or enter the ad hoc network, or as existing nodes leave or exit the ad hoc network.
In many wireless communication networks, it is desirable to determine the location or position of a node within that network. In conventional locationing or positioning technologies, a location or position of a node is typically represented by a point (i.e., a set of coordinates) and a simple indication of the accuracy or precision of that position. For instance, the location or position of the node can be represented using a circle of radius (r) that originates from a point (x,y), where the radius (r) of the circle represents the accuracy or precision of that position.
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